Developmental effects

Developmental Refei-ence Dose (RfDji) An estimate (with an uncertainty spanning perhaps an order of magnitude or greater) of an exposure level for the human population, including sensitive subpopulations, that is likely to be without an appreciable risk of developmental effects. Developmental RfDs are used to evaluate the effects of a single exposure event. 

WHO (2004) concluded that The mono- and disubstituted compounds that may leach from PVC water pipes for a short time after installation are primarily immunotoxins although they appear to be of low general toxicity, some are developmental toxins in rodents. The data available are insufficient to permit the proposal of guideline values for individual dialkyltins or the mono derivatives, although the concentrations observed in drinking-water are several orders of magnitude lower than the doses reported to cause developmental effects in rats and mice. ... 

Developmental Effects. Adverse effects of methyl parathion on hirman fetal development have not been reported. Based on studies in animals, such effects appear to be possible if pregnant women were exposed during the first trimester to high concentrations of methyl parathion that resulted in significant depression of cholinesterase levels, particularly if concomitant signs and symptoms of organophosphate intoxication occur. Such an exposure scenario may occur with occupational exposure, exposure in homes or offices illegally sprayed with methyl parathion, or accidental exposure to methyl parathion, but is less likely as a result of low-level exposure. 

No studies were located regarding developmental effects in humans or animals after inhalation exposure to methyl parathion. 

No dose-response relationship can be established for the developmental toxicity of methyl parathion from the available database. All reliable LOAEL values in rats for developmental effects for the acute- and intermediate-duration categories are recorded in Table 3-3 and plotted in Figure 3-2. 

Acetylcholine, acetylcholinesterase, and butyrylcholinesterase are involved in the development of the nervous system (Brimijoin and Koeninsberger 1999 Layer 1990 Layer and Willbold 1994) some of this development is not complete until adulthood. Therefore, toxic chemicals acting on these substances could cause deleterious developmental effects in addition to the typical physiological effects already discussed. 

Sever EE, Arbuckle TE, Sweeney A. 1997. Reproductive and developmental effects of occupational pesticide exposure The epidemiologic evidence. Occup Med 12 305-325. 

Developmental Toxicity—The occurrence of adverse effects on the developing organism that may result from exposure to a chemical prior to conception (either parent), during prenatal development, or postnatally to the time of sexual maturation. Adverse developmental effects may be detected at any point in the life span of the organism. 

The data in animals are insufficient to derive an acute inhalation MRL because serious effects were observed at the lowest dose tested (Hoechst 1983a). No acute oral MRL was derived for the same reason. The available toxicokinetic data are not adequate to predict the behavior of endosulfan across routes of exposure. However, the limited toxicity information available does indicate that similar effects are observed (i.e., death, neurotoxicity) in both animals and humans across all routes of exposure, but the concentrations that cause these effects may not be predictable for all routes. Most of the acute effects of endosulfan have been well characterized following exposure via the inhalation, oral, and dermal routes in experimental animals, and additional information on the acute effects of endosulfan does not appear necessary. However, further well conducted developmental studies may clarify whether this chemical causes adverse developmental effects. 

Colborn T, Vom Saal FS, Soto AM. 1993. Developmental effects of endocrine-disrupting chemicals in wildlife and humans. Environ Health Perspect 101(5) 378-384. 

Bosveld, A.T.C. (2000). Biochemical and developmental effects of dietary exposure to PCBs 126 and 153 in common tem chicks. Environmental Toxicology and Chemistry 19, 719-730. 

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